Apparatus for production of cold



Sept. 12, 1933. P. SCHOLL APPARATUS FOR PRODUCTION COLD jfiveizfor A 'Paz/Z JGIYUZL. 13

Patented Sept. 12, 1933 UNITED STATES PATENT OFFICE Paul Scholl, Berlin-Charlottenburg, Germany, assignor, by mesne assignments, to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application December 26, 1929, Serial No. 416,514, and in Germany December 22, 1928 3 Claims.

My invention relates to improvements in processes and apparatus for the production of cold, more particularly for electric household refrigerator cabinets.

Compression refrigerating machines as frequently used in the production of cold, more particularly for operating household refrigerator cabinets, are as a rule operated in such a manner that comparatively short working periods of the compressor alternate with comparatively long intervals during which the compressor does not work. This renders it necessary to store the cold, for instance by means of brine, if too frequent starting and stopping of the machine is to be avoided. The object of my invention is to avoid the drawbacks mentioned (for instance the indirect cooling action and the consequent necessity of lower evaporation temperatures, the limitation of the radiation of heat from the condenser to the working periods of the compressor and the necessity of intensive condenser cooling) and to provide a compression refrigerating machine which combines simple construction with economical operation and enables a continuous output of the evaporator as well as a continuous dissipation of heat to the atmosphere or other cooling medium.

According to my invention the object aimed at is attained by means of an intermittently acting compression refrigerating machine and an absorptionvessel serving for the temporary reception of the gaseous working medium during the time when the compressor is inoperative. When the compressor is operated the gaseous working medium then evaporates out of the absorption liquid without the expenditure of external heat merely in consequence of the drop in pressure connected with the operation of the compressor and the dropping of the evaporator temperature. During this portion of the cycle, the absorption liquid may absorb heat from the motor and compressor which may be in the vicinity of the absorption vessel. The absorption vessel may form part of the conduit which conveys refrigerant gas from the evaporator to the compressor. A particularly suitable arrangement is one where the compressor or better still the machine unit consisting of compressor and driving motor is placed into the absorption liquid. In this way, the noise of the compressor is considerably reduced. Other advantages will be pointed out as the specification proceeds. It may also be advisable to arrange the condenser in the absorption liquid. It is then possible to manage with a considerably smaller condenser area than if the condenser were directly cooled by air.

In the accompanying drawing,

Fig. 1 is a diagrammatic representation of a compression refrigerating machine provided with an absorber for carrying out the principles of the present invention and Fig. 2 is a diagrammatic representation of a modified form. of construction embodying the principles of the invention.

Referring to the embodiment of my invention illustrated in Fig. l of the drawing it will be noticed that in the upper part of the refrigerator cabinet 1 there is located the evaporator 2 in form of a cooling coil. To the upper end of the evaporator 2 is connected a pipe 3 which passes into a vessel 4 located upon the refrigerator cabinet 1 and opens below the level of an absorption liquid 5 (aqueous ammonia solution) in this vessel. The absorption vessel 4 is on its circumference provided with radiation ribs or the like 6. The absorption solution 5 does not fill the chamber formed by the vessel 4 completely but leaves a space which is connected by pipe '7 with a small vessel 8 serving as a liquid separator. From the .80 separator 8 a gas pipe 9 leads to the suction side of the compressor 11 which together with its driving motor 10 is located in the absorption liquid'5. The shaft common to the machine unit is passed through stufiing boxes. From the pressure side of the compressor 11 a pipe 12 leads to a pipe 13 lielically coiled around the ribs 6 and which forms the condenser of the refrigerating machine. The end of the pipe 13 is connected to a pipe 14 terminating in a reduction valve 15. Through this valve the liquid refrigerant supplied through the pipe 14 passes into the evaporator 2 and due to the lower pressure prevailing there, evaporates.

The arrows indicate the direction in which the working medium circulates through the refrig'erating machine. The evaporator 2 may be provided with an automatically operating electric switch, not shown in the drawing for controlling the running time of the compressor motor 10. As is well known in the art, mechanism may be so designed that the compressor motor is started or stopped when a predetermined upper or lower pressure or temperature limit is reached.

The above described compressor refrigerating machine is operated in the following manner: when current is supplied to the compressor motor 10, compressor 11 becomes operative. It then draws gaseous refrigerant (ammonia) in through the pipe 9, separator 8 and tube 7. Liquid carried into the separator 8 is returned thru the the compressor.

centration during the is operating. During this portionof the cycle, the condenser condenses the quantities of gase- -til the upper pressure tube 7. At this time the gas space of the absorption vessel 4 is at substantially the same low pressure as that in the evaporator and is filled with gaseous refrigerant ,(ammonia) which enters from the evaporator 2 through the pipe 3 below the level of the absorption liquid 5. The refrigerant drawn in and condensed by the compressor 11 passes through the pipe 12 into the condenser 13 and is here condensed or liquefied upon thedischarge of heat to the surroundings. The pipe 14 passes the condensate to the reducing valve 15. The condensate passing through the valve is relieved of its pressure and evaporates in the evaporator ,2 to produce a cooling effect. The evaporated working medium returns through the pipe 3 and the absorption liquid 5 into the gas space of the absorption vessel 4.

Absorption does not take place at this time because the gas pressure existing above the absorption liquid is low. As long as the compressor 11 is operating the pressure in the evaporator 2 and vessel 4 is maintained low and refrigerant evaporates from its liquid phase in the evaporator and is conveyed to the compressor as in an ordinary compression refrigerating system.

I When the compressor is started after a period of inactivity, refrigerant also evaporates from the solution in the vessel 4. As will be explained presently, the solution in the vessel 4 has been strengthened during the period of inactivity of As is well known a refrigerant will evaporate from a solution of a given concentration and reduced to a critical point. When the compresthe vessel 4 and take up heat from the motor 10, compressor 11 and ribs 6. The absorption solution 5 thus undergoes a desired reduction in contime that the compressor ous refrigerant coming from the evaporator as well as that evaporated out of the absorption I liquid.

If now the temperature and pressure in the evaporator 2 have dropped down to the predetermined lower' limit the compressormotor 10 is switched off automatically and the compressor 11 shut down. Although no further withdrawal of refrigerant from the gas space of the absorption vessel 4 takes place at this time, evaporation of refrigerant in the evaporator continues although to a slightly less extent, it being now absorbed by the absorption liquid'5. The rise in pressure in vessel 4 necessary for absorption is brought about as the temperature and-pressure in the evaporator rises. The described operation of the evaporator continues, assuming there is a suflicient store of refrigerant condensate unlimit at which the automatic motor switch is set is again attained and the compressor is started again. The cycle of operation then commences'again, i. e. gaseous working medium is again evaporated from the absorption solution 5, drawn in by the compressor 11 and condensed.

In this way periods of work and rest of the compressor alternate while the production of cold in I the evaporator goes on continuously. The heat of absorption generated in the vessel 4 during the stoppage of the compressor is discharged towards the outside by the radiating ribs 6. As long as no equilibrium is set up between the heat generated and the heat given oif temperature if the pressure is condenser and also from the vessel 4 if absorption liquid 5, thus reducing the total heatcontained in the latter and providing means for quickly storing up and later dissipating the heat generated by the motor and the compressor. Because of the fact that heat is dissipated when the motor and compressor are not running, the

area of the radiating surface may be'comparatively small.

A further advantage is that the evaporator may be small on account of the fact that it may operate continuously. 'A considerable saving in materials and weight is thus effected in the entire apparatus and useful cooling space is gained by the elimination of a brine tank or other indirect cooling system.

The location of the motor and compressor in the absorption liquid produces particularly favorable conditions for the discharge of the heat generated thereby. This circumstance renders it possible to manage with a smaller size motor at an equal motor output and to effect savings in this way also.

The advantages recited above may be still further increased if as shown in Fig. 2 of the drawing not only the motor and compressor are immersed in the absorption liquid but also the condenser. erence numerals like those in Fig. 1 of the drawing and only modified parts or differently located parts are marked with different reference numerals. In contrast with the embodiment illus trated in Fig. l, the motor shaft of Fig. 2 is not passed through stufiing boxes but located vwithin an intermediate member 21'by which the housing of the compressor 23 is in gas communication with the totally enclosed motor 22. In this way, the motor is effectively sealed from the absorption liquid and the stuffing boxes are eliminated.

By locating the condenser 24 within the absorption liquid 5 the cooling conditions of the condenser itself are greatly improved. The evaporation of the refrigerant from the absorption solution is furthermore accelerated since the total heat of condensation is absorbed by the absorption liquid besides the waste heat originating from the motor and the compressor. V Such an intensified gas development may, for instance, be desirable if as large as possible an output of cold is to' be obtained. This is, however, possible only at the expense of a reduction of the useful concentration range of the absorption solution and thus requires a larger quantity of absorption solution. However, intensified evaporation permits the use of a smaller quantity of absorption solution at an equal output of cold. It is well known in the art that under otherwise equal conditions, more gaseous refrig'erant may be evaporated out of an absorption solution the less its temperature 'drops during the evaporation and, on the other hand, more refrigerant may be absorbed by the solution the less its temperature rises during the absorption process. The additional heating of'tiie absorption. solution by the heat discharged from the Ill) Like'parts are here indicated by ref condenser 24 during the part of the cycle when the compressor is running thus permits evaporation of refrigerant from the solution to a lower concentration limit at the-same time the condenser is effectively cooled when it is discharging heat, most of the heat being stored in the solution and dissipated later. Tris is a particular advantage of my invention While it was necessary to provide a condenser with a large heat radiating surface and sometimes means for artificially cooling (such as a fan) in an ordinary compression refrigerating system, on account of the necessity of discharging the total heat of condensation during the working period of the compressor, it is possible, with an appararatus designed in accordance with the present invention to reduce the area of the means necessary for cooling the condenser due to the distribution of the heat discharge over a longer period of time.

I claim as my invention:

1. In apparatus for carrying out the refrigerating process herein described, an evaporator, a motor-driven compressor, an absorption vessel having absorption liquid therein, a gas pipe connecting said absorption vessel with said evaporator and opening into said absorption vessel below the level of the liquid, and a second gas pipe connecting the gas space of said absorptionvessel with the suction side of said compressor, said compressor being located in the absorption liquid.

2. In apparatus for carrying out the refrigerating process herein described, an evaporator, a motor-driven compressor, an absorption vessel having absorption liquid therein, a gas pipe connecting said absorption vessel with said evaporator and opening into said absorption vessel below the level of the liquid, and a second gas pipe connecting the gas space of said absorption vessel with the suction side of said compressor, said compressor and its driving motor being located in the absorption liquid.

3. In a compression refrigerating system, the combination of an intermittently operable compressor, a condenser and an absorption vessel associated therewith, means for causing the absorption of refrigerant in a liquid in said absortion vessel accompanied by the dissipation of heat to a cooling medium during the time when said compressor is not operating, means for causing the evaporation of refrigerant from the liquid in said absorber during the time when said compressor is operating and means for transferring heat from the compressor and the condenser to the liquid in the absorption vessel during the time when the compressor is operating.

PAUL SCHOLL. 

